1. Field of the Invention
The present invention relates generally to scanners and scanning methods, and more particularly to those permitting the capture of high resolution images of an original that is illuminated by a light source that is located outside of the optical field of view of an image detector.
2. Description of the Related Art
Scanning devices are used in a variety of applications. Scanning devices may be combined in an all-in-one unit that includes scanning, printing, and facsimile function. Scanning devices may also be independent and only capable of scanning documents. Historically, scanning devices include a drive mechanism that moves a scan bar across a target document. Each line of the document is individually scanned and the data is downloaded to a processor. This data is combined together to form a final two dimensional image of the document. These scanning devices require precise movement of the scan bar to prevent registration defects. Quality scans require intricate mechanisms which are often costly and complex.
Scanning devices, either of the all-in-one or independent variety, are popular for both business and personal use. Ideally, the devices are designed to have a smaller size that enables placement within small workspaces such as desk tops and bookshelves. As a result, size is often an important aspect when deciding to purchase a scanning device. Smaller devices are usually more accepted because of the ability to fit where needed and occupy a minimum space. Along with size, the price of the device is another important aspect during purchase. A device meeting other requirements may not be acceptable because of an higher price.
Digital photography technology has progressed with imaging units now able to produce high quality two dimensional images in a single capture step. Image sensors including millions of light sensors are readily available. The imaging units are also economical allowing them to be utilized in new applications, such as document scanning technology. The imaging unit includes a substantial field of view that is visible by the image sensor. Thus, the imaging unit is able to capture most or all of a document original. Unfortunately, the relatively large field of view creates space and illumination complications. The image sensor may include a relatively large focal length. Further, stray reflections may be prone to enter the field of view and reach the sensor. Accordingly, scan devices incorporating these types of imaging units should accommodate these problems.